State of the art in large-scale soil moisture monitoring

Authors: OCHSNER, T - Oklahoma State University; Cosh, Michael; CUENCA, R - Oregon State University; DORIGO, W - Vienna University Of Technology; DRAPER, C - National Aeronautics And Space Administration (NASA); HAGIMOTO, Y - Oregon State University; KERR, Y - Collaborator; LARSON, K - University Of Colorado; NJOKU, E - Jet Propulsion Laboratory; SMALL, E - University Of Colorado; ZREDA, M - University Of Arizona

Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/21/2013
Publication Date: 11/1/2013
Publication URL: http://handle.nal.usda.gov/10113/59839
Citation: Ochsner, T., Cosh, M.H., Cuenca, R., Dorigo, W.A., Draper, C., Hagimoto, Y., Kerr, Y., Larson, K., Njoku, E., Small, E., Zreda, M. 2013. State of the art in large-scale soil moisture monitoring. Soil Science Society of America Journal. 77(6):1888-1919.

Interpretive Summary: Soil moisture at the surface is essential to the understanding of the land atmosphere interface, yet it is difficult to directly measure it on a large scale. The monitoring of soil moisture has reached new heights recently with the launch of several satellite platforms, which have as their central purpose, the estimation of surface soil moisture. There are also several new measurement technologies, which have begun deployment to estimate soil moisture on a large scale. These technologies add to the more traditional methods of monitoring, such as national soil moisture and climate networks. This review will examine each of the current and new technologies used for estimating soil moisture and compare their advantages and disadvantages. This will provide an opportunity for the diverse communities, which use these technologies to discuss their theoretical approaches to soil moisture estimation and to find commonalities. Each of these communities will be able to improve their own methods, by expanding their base of knowledge.

Technical Abstract: Soil moisture is an essential climate variable influencing land-atmosphere interactions, an essential hydrologic variable impacting rainfall-runoff processes, an essential ecological variable regulating net ecosystem exchange, and an essential agricultural variable constraining food security. Large-scale soil moisture monitoring has advanced in recent years creating opportunities to transform scientific understanding of soil moisture and related processes. These advances are being driven by researchers from a broad range of disciplines, but this complicates collaboration and communication. And, for some applications, the science required to utilize large-scale soil moisture data is poorly developed. In this review, we describe the state of the art in large-scale soil moisture monitoring and identify some critical needs for research to optimize the use of increasingly available soil moisture data. We review representative examples of 1) emerging in situ and proximal sensing techniques, 2) dedicated soil moisture remote sensing missions, 3) soil moisture monitoring networks, and 4)applications of large-scale soil moisture measurements. Significant near-term progress seems possible in the use of large-scale soil moisture data for drought monitoring. Assimilation of soil moisture data for meteorological or hydrologic forecasting also shows promise, but significant challenges related to spatial variability and model structures remain. Little progress has been made in the use of large-scale soil moisture observations within the context of ecological or agricultural modeling. Opportunities abound to advance the science and practice of large-scale soil moisture monitoring for the sake of improved Earth system monitoring, modeling, and forecasting.